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capture promoted Tier 1 2026-07-06

Capture: Did Crick (1989) 'The recent excitement about neural networks' (Nature 337:129–132) first formally state the weight transport problem, predating Hinton's 2022 formulation?

This capture follows up a claim flagged in the 2026-06-30 capture on what Hinton meant by calling backpropagation biologically implausible, asking whether Crick's 1989 Nature commentary "The recent excitement about neural networks" (vol. 337, pp. 129–132) was the first formal statement of the weight transport problem, predating Geoffrey Hinton's 2022 formulation of the same idea.

Bottom line up front: the premise does not hold. Crick's 1989 objection to backpropagation's biological plausibility is real, primary-sourced, and directly read for this capture — but it is a different mechanistic objection from the weight transport problem, not an early statement of it. The term itself is attributed elsewhere, to an earlier source. And Hinton's 2022 paper is not really a rival "formulation" to be predated — it doesn't use the term at all. Each piece is detailed below with exact quotes and full provenance.

Claim: Crick's 1989 Nature commentary exists as described — "The recent excitement about neural networks," Nature vol. 337, 12 January 1989, pp. 129–132, single-author commentary by Francis Crick, Salk Institute

Claim type: historical/bibliographic, uncontested. Tier 3-4 acceptable; Tier 1 achieved.

The article was located as a page-scan (the genuine Nature typesetting) and read directly, page by page, rather than relayed through a summary. The masthead reads "NATURE VOL. 337 12 JANUARY 1989 · COMMENTARY," p. 129, byline "Francis Crick," and the piece closes: "Francis Crick is at The Salk Institute, PO Box 85800, San Diego, California 92138-9216, USA."

Provenance:

Claim: Crick's actual stated objection to backprop's biological plausibility is that it would require backward transmission of information along the axon ("antidromically" from each synapse) — not that it requires weight symmetry between forward and backward pathways

Claim type: specific technical-mechanism claim. Tier 1-2 required — Tier 1 achieved (primary text read directly, in full, this session).

Under the heading "Neural nets and the brain" (p. 131, right column):

"It is hardly surprising that such achievements have produced a heady sense of euphoria. But is this what the brain actually does? Alas, the back-drop nets are unrealistic in almost every respect, as indeed some of their inventors have admitted. They usually violate the rule that the outputs of a single neuron, at least in the neocortex, are either excitatory synapses or inhibitory ones, but not both. It is also extremely difficult to see how neurons would implement the back-prop algorithm. Taken at its face value this seems to require the rapid transmission of information backwards along the axon, that is, antidromically from each of its synapses. It seems highly unlikely that this actually happens in the brain."

Under the heading "Why the excitement?" (p. 131, right column, near the bottom):

"Nevertheless, as far as the learning process is concerned, it is unlikely that the brain actually uses back propagation."

Note the second sentence is the source of the widely-circulated paraphrase "it is very unlikely that the brain uses back propagation" — the actual text says "unlikely," not "very unlikely"; "highly unlikely" is a separate word choice attached to the antidromic-transmission sentence, not this one. Secondary retellings appear to have merged the two sentences.

Neither sentence, nor any other passage in the four-page article, mentions weight symmetry, transposed weight matrices, or the feedback pathway needing to reuse the forward pathway's weight values. The full text was read directly, page by page (all four pages of the commentary plus its 24-item reference list), and the words "symmetric," "transpose," and "weight transport" do not appear anywhere in it. Crick's separate, related objection on the same page — that back-prop nets "violate the rule that the outputs of a single neuron ... are either excitatory synapses or inhibitory ones, but not both" — is a Dale's principle-type objection, also distinct from weight transport.

Provenance:

Claim: the term "weight transport problem" was named by Stephen Grossberg (1987), predating Crick's paper by two years; Lillicrap et al. (2016) describe Crick's 1989 objection as "echoing" concerns already raised by Grossberg and by Zipser & Rumelhart, not as the term's origin

Claim type: historical/attribution claim, escalated per the rubric's own example (an attribution claim that reassigns priority away from a well-known name is exactly the kind of "surprising, load-bearing" historical claim the floor says needs Tier 1-2, not a Tier 3-4 pass-through). Tier 1-2 required — Tier 1 achieved for the attribution itself (though see the caveat below on Grossberg's own text).

Source: Lillicrap, Cownden, Tweed & Akerman, "Random synaptic feedback weights support error backpropagation for deep learning," Nature Communications 7:13276 (2016). Read directly via PMC full text.

"This issue was described in detail by Grossberg, who named it the weight transport problem. ... Weight transport was also identified as a major problem by Zipser and Rumelhart, and their concerns were echoed by Crick who noted that, when taken at face value, backprop seems to require rapid information transfer back along axons from each of its synaptic outputs."

Reference list entries (as read directly):

Caveat, stated plainly rather than smoothed over: Grossberg's own 1987 paper was not independently accessed this session — ScienceDirect and Wiley both blocked the fetch attempt (403 Forbidden) — so the claim "Grossberg named the term" rests on Lillicrap et al.'s say-so (a Tier 1 peer-reviewed source making a direct historical attribution) rather than on Grossberg's own words. This is Tier 1-sourced but not doubly-verified against the ultimate primary text; a future session should try to pull the Grossberg 1987 Cognitive Science paper directly.

Also worth flagging as a chronological wrinkle: Zipser & Rumelhart (1990) — cited by Lillicrap et al. as one of the sources Crick's 1989 concern "echoed" — was published a year after Crick's paper. Crick's own reference list cites a different Zipser paper (Zipser & Andersen, Nature 331, 679–684, 1988, on parietal-neuron modeling), not Zipser & Rumelhart. So Crick could not have been echoing the 1990 Zipser & Rumelhart chapter chronologically; if anything the influence, if any existed, would run the other way, or the two are independent.

Provenance:

Claim: Hinton's 2022 "The Forward-Forward Algorithm: Some Preliminary Investigations" (arXiv:2212.13345, submitted 27 December 2022) discusses backpropagation's biological implausibility in general terms, but does not cite Crick (1989) anywhere and does not use the literal phrase "weight transport problem" anywhere in the paper — it gestures at the same underlying issue only in a footnote citing Lillicrap et al. (2016) and Lillicrap et al. (2020)

Claim type: technical-mechanism / historical (an absence claim about a specific primary text). Tier 1-2 required — Tier 1 achieved, via direct reading of the primary source itself (abstract/metadata independently confirmed this session; full-text passages, footnotes, and the complete 16-page reference list read and reported by a research subagent that downloaded the PDF directly).

Section 1, "What is wrong with backpropagation" (pp. 1–2):

"As a model of how cortex learns, backpropagation remains implausible despite considerable effort to invent ways in which it could be implemented by real neurons (Lillicrap et al., 2020; Richards and Lillicrap, 2019; Guerguiev et al., 2017; Scellier and Bengio, 2017). There is no convincing evidence that cortex explicitly propagates error derivatives or stores neural activities for use in a subsequent backward pass. The top-down connections from one cortical area to an area that is earlier in the visual pathway do not mirror the bottom-up connections as would be expected if backpropagation was being used..."

"A further serious limitation of backpropagation is that it requires perfect knowledge of the computation performed in the forward pass in order to compute the correct derivatives."

Footnote 2 — the closest the paper comes to the weight-transport idea, without naming it:

"It is possible to use random weights in the backward pass instead of the transpose of the forward weights, and this yields fake derivatives that work surprisingly well on small-scale tasks like MNIST (Lillicrap et al., 2016), but it does not scale well to large networks and it is particularly bad at squeezing information through narrow bottlenecks."

The paper's reference list (pp. 14–16) does not include Crick (1989) at all, and the phrase "weight transport problem" does not appear anywhere in the document's body text.

Provenance:

Central question status

Did Crick (1989) first formally state the weight transport problem, predating Hinton's 2022 formulation?

Premise not supported — refuted on the evidence gathered, not merely unverified. Three independent findings, each Tier 1-sourced, undercut the premise:

  1. Crick's actual stated mechanistic objection is that backprop would require backward signal transmission along the axon ("antidromically from each of its synapses") — a different claim from weight transport (the requirement that the backward pathway use the same, or transposed, weight values as the forward pathway). The words "symmetric," "transpose," and "weight transport" appear nowhere in Crick's four-page article, confirmed by direct reading.
  2. Per Lillicrap et al. (2016), a Tier 1 peer-reviewed source, the term "weight transport problem" was named by Grossberg (1987) — two years before Crick's paper — with Crick's concern characterized as an echo of concerns raised by Grossberg and by Zipser & Rumelhart, not as the origin of the idea or the term. (Caveat: this rests on Lillicrap et al.'s attribution; Grossberg's own 1987 text was not independently accessed this session.)
  3. Hinton's 2022 Forward-Forward paper does not itself "formulate" the weight transport problem in any formal sense — it never uses the phrase, and it does not cite Crick at all. It only gestures at the underlying issue in a single footnote citing Lillicrap et al. (2016, 2020). There is no head-to-head "formulation" by Hinton in 2022 for a 1989 Crick statement to predate.

So the compound claim in the topic prompt collapses on all three legs: Crick did not state the weight-transport/symmetry problem specifically (he stated a different, related objection), the term itself has an earlier and different origin (Grossberg 1987), and Hinton's 2022 paper is not a rival "formulation" of the term to be predated in the first place.

Further leads

Source

Tier 1 Francis Crick 1989-01-12
https://apsc450computationalneuroscience.wordpress.com/wp-content/uploads/2019/01/crick1989.pdf
· batch run 2026-07-06 — researched via web search/fetch and direct reading of the primary Nature scan, the Lillicrap et al. 2016 Nature Communications paper, and Hinton's 2022 arXiv preprint; harvested from 2026-06-30-what-exactly-did-geoffrey-hinton-mean-by-calling-backpropagation-biologically-implausible · raw markdown